This application relates to an oral rinse for the disruption of plaque from teeth, and relies upon applicants' discovery that the incorporation of orthophosphates leads to substantial removal of plaque.
Dental plaque is present to a greater or lesser extent on virtually all dental surfaces. Dental plaque is composed of closely matted microorganisms in a matrix made from polysaccharides, proteins and other materials which are, at least in part, of salivary origin. The microorganisms are mainly coccoidal, especially in early plaque, changing in some mouths to filamentous organisms after a few days. Dental plaque presents a significant problem to dental health for several reasons. First, evidence indicates that the microorganisms in dental plaque are a primary factor in dental caries. In addition, the prime etiologic factor in periodontal disease, including gingivitis, is dental plaque.
Moreover, dental plaque is a precursor in calculus formation. Dental calculus (tartar) forms on the surfaces of teeth at the gingival margin and promotes periodontal breakdown by increasing undesirable products in the crevicular pocket area. Supragingival calculus appears principally near orifices of salivary ducts e.g. on lingual surfaces of the lower anterior teeth, on buccal surfaces of the first and second molars, and on the distal surfaces of the posterior molars. In addition to being unsightly from an aesthetic viewpoint, calculus is a constant source of irritation to the gingiva and can make toothbrushing a painful procedure.
Because of these problems associated with plaque, it is important to find means to reduce plaque accumulation on teeth. Regular brushing with a conventional dentifrice for some persons can retard or even prevent the accumulation of significant amounts of dental plaque and calculus. For other persons, however, the plaque film builds up rapidly even with regular brushing, which, in turn, leads to the formation of calculus. Removal by a dentist is the most common method available for individuals to prevent the undesirable consequences of the accumulation of significant amounts of dental calculus. Recently, however, dental rinses have been developed with the stated purpose of loosening plaque on dental surfaces to facilitate its removal during brushing. For example, U.S. Pat. No. 4,657,758, incorporated herein by reference, describes a dental rinse which is an alkaline solution of a surfactant and a detergent builder.
It has now been found that orthophosphates, particularly alkali metal orthophosphates and ammonium orthophosphates, when used in a concentration of about 1.2% to about 10.0% by weight in an oral rinse at pH 5.5-10.5, are highly effective in removing plaque on teeth. While orthophosphates have been used in dental preparations, the ability to act as plaque loosening and removing agents, to applicants' knowledge, has not been recognized. For example, alkali metal phosphate has been shown to be effective in reducing dental caries when added to cariogenic rodent diets. (Nizel et al., J. Dent Res. Supp. to No. 6, 43, 1123 (1964)). A similar result was noted in hamsters, along with the further observation that continuous administration of the phosphate supplement is required to attain this anticaries effectiveness (Englander et al., J. Dent. Res. 49(1), 140 (1970)). This effect has been attributed to a modification of the composition of the protein layer adsorbed on tooth enamel. (Pruitt et al., Nature 225, 1249 (1970)).
Alkali metal phosphates have been used in fluoride dentifrices. U.S. Pat. No. 4,198,394 claims a dentifrice containing sodium dihydrogen phosphate (0.03-0.4%) and stannous fluoride (0.03-0.4%) with a pH of about 2.5 to about 5.5. U.S. Pat. No. 4,565,691 presents an oral hygiene composition which contains alkali metal phosphates in a fluoride-containing dentifrice which utilizes dicalcium phosphate dihydrate, as the abrasive. The phosphates are added to maintain fluoride availability. U.S. Pat. No. 4,254,101 presents dentifrice formulas in which alkali metal phosphates are used as buffers in a fluoride-containing dentifrice. None of these patents are concerned with clear dental rinses or mouthwashes.
Orthophosphates have also been used in certain oral rinses, to protect enamel. For example, an acidulated phosphate fluoride dental rinse from sodium fluoride, acidulated with a mixture of sodium phosphate, monobasic, and phosphoric acid to a level of 0.1M phosphate ion and a pH of 3.0-4.5 is recognized as an over-the-counter anticaries dental rinse drug product [Federal Register, 50 (No. 89):39854-39873, Sept. 30, 1985]. The phosphates are present to protect enamel at the low pH specified.